Krell FPB 700cx
|The Sound and the Fury
4 February 2003
700 Wpc into 8 Ohms
1400 Wpc into 4 Ohms, 2800 Wpc into 2 Ohms
Frequency response: 20 Hz to 20 kHz, +0 db, -3 db
Signal to noise ratio: 120 db
Gain: 26.4 db
THD: 1 kHz <0.03%
Input impedance: 100 ohms
Standby: 85 W
Idle: 430 W
Max: 6000 W
19" W × 10.3" H × 25.5" D
Krell Industries, Inc
45 Connair Road
Orange, CT 06477-3650
Telephone: 203-799 -9954
Those floors are reinforced…right?
At the moment, my living room looks
like a parking lot occupied by the big and brawny
amplifiers of today's who's-who in solid-state
amplification. In the corner sits the unfailingly
musical Jeff Rowland Design Group Model 8TiHC stereo
amp. Simmering in the wings one finds the facile yet
muscle bound Pass X600 mono blocks, parked squarely
between the Talon Khorus X loudspeakers, and the
subject of this review, rests the new Krell FPB 700cx
700 Wpc stereo amplifier.
Aside from the cool factor of having all this
cutting-edge heavy metal in house, each amplifier
mentioned above posses great yet unique strengths
that have enabled me to solidify my observations
regarding the FPB 700cx. While it's a ton of
schlepping from one 150+ pound amp to the next, it
was well worth the exercise in order to get a firm
grasp on the sound of the FPB 700cx and how its
performance compares to the established benchmarks.
Anatomy of the Beast
If you have never seen the FPB
700cx in person, you are in for a shock. This thing
is HUGE! While the Pass X600 mono blocks collectively
take up more square footage, the 180 pound, single
chassis stereo FPB 700cx is the dominating presence
in the room. This is not to say there is anything
objectionable about the design of the FPB 700cx - far
from it, in fact! Everything about the amp screams
quality, if from a more masculine perspective than,
say, the gleaming and polished Rowland 8TiHC.
The rear of the amp sports two pair of reviewer
friendly, extra large wing nut clad binding posts.
Man, I love those things. Inputs include 1 pair of
balanced inputs, 1 pair of single ended inputs and
Krell's proprietary CAST II inputs. The CAST
technology allows for the signal to be transmitted in
the current rather than voltage domain. This is said
to produce a wider bandwidth signal and allows for
super long runs of cable with no cable-induced
distortions. I can't comment one way or the other
regarding the benefits of the CAST II option since I
don't have a Krell front end equipped with the CAST
II out-puts. The FPB 700cx also employs Krell's
Sustained Plateau Biasing III, the third generation
of the biasing technology introduced nearly a decade
ago. The CAST circuit efficiency is said to address
the issues of excessive energy consumption and heat
generated by traditional class-A biased designs.
While the FPB 700cx did get hot when pushed, it
remained relatively cool when idle. More information
on the CAST system and the plateau biasing technology
is available at the
As with all the later FPB series amplifiers, the
power cord is captive, prohibiting any after market
power cord experimentation. While Krell may well have
its reasons for this, I for one would have loved to
harness the FPB 700cx to the new Shunyata Anaconda
power cord that has proved itself so extraordinary
with my other electronics.
Is the Past Really Past?
I reviewed the last generation FPB
600c a couple of years ago and found it to be very
strong in all areas save the upper octave extension,
a slight lack of midrange accuracy and soundstage
transparency. Collectively, the shortcomings added up
to a darkened over-all character as opposed to the
sunnier high frequency perspective offered by the
Pass X600 or the accurate mid-band portrayal of the
While I don't know if the FPB 700cx I received had
been burned in at the factory, I can say that it
sounded very good right out of the box. With an
inviting over-all signature, dynamically alive from
top to bottom and that bottom octave control that is
truly unique to Krell amplifiers, the FPB 700cx made
a great if familiar first impression.
Through the first few days of listening, my
experiences with the FPB 600c came flooding back.
Rock solid imaging, a huge soundstage and yes, the
bass. Yet the following days revealed attributes that
have never in my experience been put forth by a Krell
amplifier to this degree. There was air there! There
was a degree of transparency that reached deeper into
the soundscape than any Krell amplifier I have heard
before. Have these attributes re-defined the Krell
sound? In answering that question, I cannot rule out
the fact that my speakers have been up-graded which
could be contributing to the heightened sense of
improvement. On its own merits however, the new Krell
700cx does put on a hell of a show, taking the FPB
700cx much further down the musical road than I had
When talking Krell, you really have to start with the
bass. Man-o-man, there is nothing like the nether
regions offered up by 700 Watts of Krell power. One
of my favorite reference bass busters, "I'm Home
Africa," from Stanley Clarks' East River Drive
(Epic EK47489), builds up a rhythmic propulsion that
is pushed along by supremely clean leading edge
transients coupled with an explosive dynamic range.
The bass on this track should be huge in impact yet
tightly focused in space. With the FPB 700cx in
charge, that is exactly what I got. While the Pass
X600s are no slouch in this area, the FPB 700cx added
a level of impact and a sense of limitless dynamic
control that contributes a great deal of drama and
excitement to the presentation. Want something truly
scary? Listen to track 1, "Devils Slide," from Joe
Satriani's Engines of Creation (Epic EK67860).
The shuddering machine gun staccato of low bass notes
took on an iron-fisted control and surprisingly, a
more accurate rendition of tonal color than the FPB
700cx's predecessor the FPB 600c. I have never heard
the woofer of the Khorus X, or the Avalon Radian for
that matter, controlled nearly to this degree. I
usually don't like to use percentages as a measure of
improvement when reviewing, but in this case, the
Krell 700cx adds at least 15% more control and
extension compared to the competition.
While controlling the bass frequencies is a trademark
of Krell amplifiers, many have complained that the
mid-band of past Krell amplifiers have been
over-controlled, too tight or lacking bloom and
color. Compared to the Jeff Rowland 8TiHC, which is
singular in solid-state mid-band performance, I would
have agreed. However, the FPB 700cx's mid range
portrayal has moved much closer to the ideal.
Listening to Nora Jones Come Away With Me
(Blue Note BN7243), with both the Krell and the
Rowland, found the gap had narrowed considerably.
Both amplifiers performed exceptionally, revealing
the strength and subtlety of Nora's exceptional
instrument while exposing the recordings inherent
flaws. Of the two amplifiers, I still give the nod to
the Rowland for recreating the organic nature of
Nora's voice. There seems to be a tad less artifice
to the timbre when compared to the 700cx. Yet the
Krell presented the song with rock solid, fleshed out
imaging and a dynamic life that left the Rowland
sounding rather gentile and tad bit timid by
comparison. Ultimately, neither the Rowland nor the
Pass amplifiers can decisively out pace the Krell's
over-all level of presence and tangibility. This is
one convincing amplifier.
Yet, there is nothing forced or forward about sound
of the FPB 700cx. It cruises along as gently as a
dove, tracking the signal with micro dynamic ease.
The upper frequencies are tonally more laid back and
remain darker than either the Pass X600 or the
Rowland. This effect gives the over-all tonal balance
more of a mid-range prominence. Having said that,
there was no sense of being shortchanged in treble
detail or focus. Which amp of the three is most
accurate? Tough call. These are three accomplished
designs that offer differing, albeit convincingly
realistic, musical perspectives.
I can say the Krell is very neutral to the source,
rendering each recording in stark contrast to the
next. Interestingly, the Krell was still rather easy
on the ears. Even some of my worst recordings, while
thoroughly exposed, were more inviting in some ways.
I chalk this up to the Krell's full-bodied imaging,
dynamic life and its ability to sort even the
subtlest musical threads within the mix.
Despite the Krell's superiority with electronic
music, I did listen to some acoustic material as
well. Track 7 from Duke Ellington's Ellington
Indigos (CK44444), presents a great sound stage
full of horns with Mr. Ellington manning the piano
smack dab in the middle and to the rear of the stage.
The texture and timbre of the horns sounded right,
fat with plenty of blat, as did the sound of the
piano. I grew up listening to my father play a 6 foot
Mason Hamlin grand in our living room day after day
for 20 years, so I have that unmistakable sound of a
real piano burned into my brain. The FPB 700cx gets a
large measure of it as right as I have heard it. That
steep attack of the mid to upper registers hammers
colliding with the strings, coupled with the
percussive yet harmonically complex left hand and
that deep rich woody resonance. Yes, it was all
there. If you want anything even a little better in
the midrange while maintaining the 700cx's virtues,
I'm afraid you are going to have to dig a whole lot
deeper into your piggy bank.
Is there any downside to the FPB 700cx? Not much of
one, as far as I'm concerned. At this level of
performance, we really are talking about personal
sonic preferences and system compatibility. As for my
personal preferences, I find the FPB 700cx extremely
engaging, particularly as far as dynamics, tonal
balance, imaging and sound staging are concerned.
However, while the 700cx has moved decidedly in the
right direction as far as the mid-band is concerned,
there remains a little room for improvement. Also,
while the bass is decidedly more powerful than its
competition, it was a little thicker sounding,
favoring mid-bass punch and low frequency extension
If you have not heard a Krell amplifier in three or
four years, go and give one a listen. This company
has come a country mile in the direction of producing
a truly satisfying amplifier. Anyone who feels his or
her system is overly forward and bright,1
you may well welcome the Krell's neutral to laid back
high-frequency perspective. As for the shortcomings,
you may well have to spend big dollars in order to
get anything decidedly better. Considering tubes? You
may achieve a heightened sense of space and liquidity
in some designs, though you also may well be giving
up a whole boat-load of virtues that the FPB 700cx
has to offer that all but the most enormous and
expensive tube amps can even come close to matching.
Perhaps the more expensive FPB 450Mcx or FPB 750Mcx
monoblocks would fill the bill, but that choice is up
to your level of audiophilia and the resilience of
Bring it on home….
The longer I participate in this
endeavor, the more I realize that there is no magic
bullet. What was just last months greatest component
since Edison's' Dictaphone often finds itself listed
on the vast audio wasteland that is Audiogon.com.
Driven by the hopes and dreams of the latest upgrade
and the hope that it will bring us everlasting
musical bliss, we are forever searching.
With the Krell FPB 700cx, I can say with certainty
that we have an amplifier that should find itself a
permanent home in all but the most obsessive, tweaky
and ultra-deep pocketed audiophile. I for one could
easily retire with an FPB 700cx and never look back.
Built with uncompromising attention to detail and
backed by a company that is in the game for the long
haul, not an insignificant point in these troubled
economic times, the FPB 700cx finds itself on a very
short list of candidates in the super-amp category.
Capable of truly engaging sound, the FPB 700cx always
kept my attention pointed were it should be,
connected to the excitement and life of the music.
While some designs and technologies may focus their
attention on perfecting a particular part of the
musical spectrum, few can match the FPB 700cx's
ability to blend its overall sonic strengths into
what is a singular musical experience.
In my opinion, most high-end systems are way to
forward and bright sounding!